Just don’t plug in the switch and in Bluetooth settings turn off “Switch Function”
But wouldn’t it always be on in that case?
Yes, why would you want to turn off charging or telemetry?
Storage. I would only turn mine on to check voltages, and to charge, as I don’t expect p-groups to need balanced.
That’s my idea as well. No need to have the BMS powered on 100% of the time. Even if minimal, it will still drain the pack slowly.
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The receiver on mine flashes iirc
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Half stuck together. It’s not pretty but feels solid and more importantly fits in the box.
I know, I know, it’s clear hot glue. Not ideal, I didn’t buy the black stuff I see everyone using.
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2nd half is glued together, we’re almost ready to start welding
Here’s what I’m considering doing. I could make it a sort of “multipurpose” pack. I’m thinking about making it so I can use it as two separate 6S packs. I already have 6S JST male and female connectors.
The reason is that when I wouldn’t use the board, I’d be able to use the 6S packs for a different hobby where… I need 6S packs. This would also allow me to charge them individually with my balance charger (which tops out at 10S, so couldn’t use it for the full pack). Another advantage is I’d have a backup way to charge it if the LTT BMS dies…
Does this sound too crazy?
Not the prettiest welds but I think they’ll hold. Taking this part slowly, I really don’t want to short anything…
If it all goes well, maybe we’ll finish up the pack tomorrow. 2nd cell section, wrap and leads are still left to do.
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This is not going to win any beauty contests, that’s for sure.
At least we have a few lessons learnt:
- I’ve bought fish paper way too thick. Not being self adhesive is also a pain. Not much to do about this, it was the only kind they had at the store and I didn’t know what to expect.
- I don’t have large shrink wrap, it would’ve been nice and make it more tidy.
- in hindsight, I would’ve been better off designing a more simple and “square” case so I could have0 made the pack like a proper brick and not a weird shape like this one.
I welded extra tabs for the balance leads, everything will be on the top, I don’t have room for wires on the sides, where the welds are. Even on the top I don’t have that much room, I wanted to leave some space for foam tape to insulate the pack from vibrations… might get too tight.
This is how I ended up connecting the main leads. Should be enough, I won’t pull more than let’s say 40A total. It’s 0.15x8mm nickel strip (the welder can’t handle more than this). I soldered the strips first to the wires, cleaned them up and welded them over the existing strip which connects the parallel cells.
If anything here looks completely wrong, please stop me.
I know, I could’ve found a way to not cross the balance leads, but I wanted to stick to my initial plan of two individual 6S packs making up the 12S. This way I’ll have two 6S balance leads.
We might run into a bit of space issue, I might have designed the box a bit too tight, I hadn’t considered that I need to route wires on top of the cells. We’ll burn that bridge later…
All connections are good, voltage reads are as expected.
Yes, I intentionally left the balance lead so short, it’ll make sense once it’s all in the enclosure.
I just tried that BMS power switch, and for me, it does absolutely nothing. The BMS is always on regardless of whether or not those red/black power wires are shorted. That’s a bit disappointing. I might email LLT and see what they say.
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Strange. I ran across a random pic around here yesterday and it showed an LTT BMS with a switch connected to that port, I assumed it works as intended.
Is there any setting to enable the switch? I haven’t powered on mine yet. Maybe later tonight, I’m working on the pack as we speak.
I’ll dig around in the settings some more.
There is indeed an option to enable a “switch circuit” but nothing changes as far as I can tell.
slight snag.
Before starting on the 2nd half of the pack I decided to do some more fine tuning of the spot welder and did some pull tests. Apparently it’s having a hard time properly welding the 0.15mm strips on the A123 positive ends. I can’t get consistent results to pass the pull test.
I did the same tests before starting on the 1st half of the pack but I think I only did with the negative ends which work much better with these strips. I think it’s a different metal (the positive ends for A123s are the same as the whole cell case), the negative ends seem different, more “shiny” if this is a clue.
Dammit. Now I don’t know what to do… I’d so not want to take the finished pack apart but I also can’t be 100% sure that all the welds are fine. I’d even more so would like to not have to get a different welder. Fusing strips to strips and strips to the A123 negative ends works great, doesn’t even need to be on the highest power setting…
Any tips here? Anything in particular I’d need to do to prep the A123 surface before welding? I did lightly sand but doesn’t seem to help…
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Yes, the wrapped pack is coming apart. I cut out just one section of a positive end and the strip popped right off with just a bit of nudge. Dammit. I might have better luck with some 0.12 nickel strip I have… might do that and stack a few layers on the main ends.
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Couple of weld pull tests can go a long way to preventing annoying rework.
hmm no point in me saying this now really sorry haha. Been there is what I meant I guess
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